On the XEM7310 (for PCB revisions prior to EXX), devices designated U16, U18, and U19 are Intel EP53F8QI.
It should be noted that the EP53F8QI is a switching power supply with a high-impedance feedback node which is sensitive to disruption from, for example, human contact. By far, the most common failure for these is related to mishandling of the product. For example, finger contact with these nodes while power is applied to the board can cause the device to fail completely or partially. In partial failure, the device can maintain regulation but may dissipate more heat than under normal operation.
Never handle the module (or any open circuit board) when power is applied. If handling is required during operation, we strongly advise customers to take precautions such as applying conformal coating. Repair or replacement due to failure of this device is not covered by warranty or repair service.